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read_dictReadDictReadDictread_dictT_read_dict🔗

Short description🔗

read_dictReadDictReadDictread_dictT_read_dict — Read a dictionary from a file.

Signature🔗

read_dict( filename.read FileName, attribute.name GenParamName, attribute.name GenParamValue, out dict DictHandle )void ReadDict( const HTuple& FileName, const HTuple& GenParamName, const HTuple& GenParamValue, HTuple* DictHandle )static void HOperatorSet.ReadDict( HTuple fileName, HTuple genParamName, HTuple genParamValue, out HTuple dictHandle )def read_dict( file_name: str, gen_param_name: MaybeSequence[str], gen_param_value: MaybeSequence[Union[int, float, str]] ) -> HHandle

Herror T_read_dict( const Htuple FileName, const Htuple GenParamName, const Htuple GenParamValue, Htuple* DictHandle )

void HDict::HDict( const HString& FileName, const HTuple& GenParamName, const HTuple& GenParamValue )

void HDict::HDict( const HString& FileName, const HString& GenParamName, const HString& GenParamValue )

void HDict::HDict( const char* FileName, const char* GenParamName, const char* GenParamValue )

void HDict::HDict( const wchar_t* FileName, const wchar_t* GenParamName, const wchar_t* GenParamValue ) (Windows only)

public HDict( string fileName, HTuple genParamName, HTuple genParamValue )

public HDict( string fileName, string genParamName, string genParamValue )

void HDict::ReadDict( const HString& FileName, const HTuple& GenParamName, const HTuple& GenParamValue )

void HDict::ReadDict( const HString& FileName, const HString& GenParamName, const HString& GenParamValue )

void HDict::ReadDict( const char* FileName, const char* GenParamName, const char* GenParamValue )

void HDict::ReadDict( const wchar_t* FileName, const wchar_t* GenParamName, const wchar_t* GenParamValue ) (Windows only)

void HDict.ReadDict( string fileName, HTuple genParamName, HTuple genParamValue )

void HDict.ReadDict( string fileName, string genParamName, string genParamValue )

Description🔗

read_dictReadDict reads a dictionary from the file FileNamefileNamefile_name and returns the handle of the dictionary in DictHandledictHandledict_handle.

The operator supports the following file formats:

  • 'hdict'"hdict": Binary HALCON format for dictionaries. Files with this format can be written by write_dictWriteDict. The default file extension for this format is 'hdict'.

  • 'json'"json": JSON (JavaScript Object Notation) file format. The default file extension for this format is 'json'.

If the given file does not exist, the operator attempts to find the file by appending the default file extensions to the filename. The file type is automatically recognized based on the file content and the file ending (which have to be consistent).

A set of additional optional parameters can be set. The names and values of the parameters are passed in GenParamNamegenParamNamegen_param_name and GenParamValuegenParamValuegen_param_value, respectively. Some of the optional parameters can only be set for a certain file type. The following values for GenParamNamegenParamNamegen_param_name are possible:

  • 'json_value_true'"json_value_true",'json_value_false'"json_value_false",'json_value_null'"json_value_null": Set the values that are used for JSON primitives. Valid JSON primitives are 'true', 'false', and 'null'. When encountering such a primitive in a JSON file, the corresponding value in the read dictionary is set to the value defined with these parameters. The value passed in GenParamValuegenParamValuegen_param_value must be a tuple of length 1.

    The default values for primitives are 11 for 'true', 00 for 'false', and 'HNULL'"HNULL" for 'null'. These parameters only have an effect when reading a JSON file.

  • 'convert_json_arrays_to'"convert_json_arrays_to": This parameter controls which HALCON-internal data type is used to represent JSON arrays. Possible values for GenParamValuegenParamValuegen_param_value are:

    • 'dict'"dict" (default): JSON arrays are converted into HALCON-Dictionaries with consecutive integer keys starting at 00. This is always possible, even if the JSON array contains further JSON arrays. However, using dictionaries might require more memory than storing the same data in HALCON tuples.

    • 'tuple'"tuple": JSON arrays are converted into HALCON tuples. If this is not possible, for example if an array contains an array, an exception is raised.

    • 'tuple_if_possible'"tuple_if_possible": JSON arrays are converted into HALCON tuples if possible, and into HALCON dictionaries otherwise.

      Note that when using this option, the structure of the returned dictionary can change even if the JSON data follows the same schema. For example, an array of 2D point coordinates of the form '{"pt": [[1,2], [3,4]]}'"{"pt": [[1,2], [3,4]]}" would be converted into an outer dictionary which contains two tuples. However, if under the same schema no points are contained in the array, the corresponding entry in the JSON of the form '{"pt": []}'"{"pt": []}" would be converted into a tuple instead of a dictionary. Code using the read dictionary must be prepared to deal with this kind of change in types.

Execution information🔗

Execution information

  • Multithreading type: reentrant (runs in parallel with non-exclusive operators).

  • Multithreading scope: global (may be called from any thread).

  • Processed without parallelization.

This operator returns a handle. Note that the state of an instance of this handle type may be changed by specific operators even though the handle is used as an input parameter by those operators.

Parameters🔗

FileNamefileNamefile_name (input_control) filename.read → (string)HTuple (HString)HTuple (string)strHtuple (char*)

File name.

File extension: .hdict, .json

GenParamNamegenParamNamegen_param_name (input_control) attribute.name(-array) → (string)HTuple (HString)HTuple (string)MaybeSequence[str]Htuple (char*)

Name of the generic parameter.

Default: [][]
List of values: 'convert_json_arrays_to', 'json_value_false', 'json_value_null', 'json_value_true'"convert_json_arrays_to", "json_value_false", "json_value_null", "json_value_true"

GenParamValuegenParamValuegen_param_value (input_control) attribute.name(-array) → (string / integer / real)HTuple (HString / Hlong / double)HTuple (string / int / long / double)MaybeSequence[Union[int, float, str]]Htuple (char* / Hlong / double)

Value of the generic parameter.

Default: [][]
Suggested values: 0, 1, 'HNULL', 'true', 'false', 'dict', 'tuple', 'tuple_if_possible'0, 1, "HNULL", "true", "false", "dict", "tuple", "tuple_if_possible"

DictHandledictHandledict_handle (output_control) dict → (handle)HTuple (HHandle)HDict, HTuple (IntPtr)HHandleHtuple (handle)

Dictionary handle.

Number of elements: DictHandle == 1

Result🔗

If the parameters are valid, the operator read_dictReadDict returns the value 2 (H_MSG_TRUE). If necessary an exception is raised.

Combinations with other operators🔗

Combinations

Possible predecessors

write_dictWriteDict

Alternatives

json_to_dictJsonToDict, create_dictCreateDict

See also

write_dictWriteDict, serialize_handleSerializeHandle, deserialize_handleDeserializeHandle

Module🔗

Foundation